Current limiter



ug.A 26, 1947. y J. RoGoFF 2,426,523

CURRENT LIMITER Filed Jan. 14, 1943 lNVENTOR JW am W Patented Aug. 26, 1947 CURRENT LIMETER Julian Eogci, New Rochelle, N. Y., assigner to Burndy Engineering Company, Inc., a corporation of New York Application January lll, i943, Serial No. 472,423

(Cl. 20G-113) 2 Claims. l

This invention relates to fusible devices for protecting electrical circuits from the detrimental eiects of short circuit currents.

In aircraft, much of the electrical equipment is designed to use extremely heavy currents for short periods of time, perhaps for six to ten seconds. However, if such equipment were to carry currents of this magnitude for longer periods of time, the heat generated by the current might permanently damage the equipment and even cause a disastrous re.

Accordingly, the primary object of my invention is to provide a current device which may be easily mounted on the structure of an airplane and on which the fusible link may be readily placed or replaced.

Another object of my invention is to provide a device which will be light in weight and small in size so that it will be suitable for aircraft use.

Still another object of my invention is to provide a fusible link which will carry electrical overloads for considerable periods of time, but which will clear very large overloads, such as those caused by dead short circuits, in a very short period of time,

Still another object of my invention is to provide a fusible link which will not be affected materially by relatively large variations in ambient temperature.

A further object of my invention is to provide a fusible link which will clear the electrical circuit without arcing or sputtering Other objects are to provide a fusible element which will function as indicated, to which a flame-proof shell has been assembled in a substantially permanent manner, and which can be instantly replaced by a limiter and associated flame-proof shell; to provide a limiting device having terminal studs which can be assembled as a unitary assembly to the aircraft structure; to provide a limiter and dame-proof shell which can be detachably engaged to the assembly-supporting base; and to provide a device of the foregoing character which shall be adaptable to mass production methods, inexpensive to manufacture and simple to install.

I accomplish these and other objects and obtain my new results as will be apparent from the device described in the following specification, particularly pointed out in the claims, and illustrated in the accompanying drawing, in which:

Fig. 1 is a plan View of my device, partially in section.

Fig, 2 is a side View of the same, partially in section.

Fig. 3 is a cross-sectional View of my device taken along the line 3-3 in Fig. 2.

Fig, 4 is a cross-sectional view taken along the line 4-15 in Fig. 2.

Referring more particularly to the drawings, reference numeral l@ designates a moulded insulating tie bar having recesses Il and l2, provided withcenter apertures i3 and lli respectively. Extending through the apertures are bolts I5 and i6, their heads ll and I8 positioned within their respective recesses ll and l2. Spacer nuts i9 and 2li lock the bolts securely to the tie bar Il).

The limiter 2l comprises two apertured head sections 22 and '423 and integrally connecting fuse link 2li, having a special shape for interrupting the circuit under predetermined conditions, as aforesaid. About the fuse link 24, two halves 25 and 2t of the llame-proof shell 21 are cemented, each of which halves are provided with two intermediate barriers Z9 and 30 respectively, forming three compartments El, 32 and 33 for containing the molten metal of the fuse link, and providing sufficient space for the expanded gases resulting from the circuit interruption.

The terminals 34 and 35 are mounted on the bolts l5 and lli, through apertures 3G and 31 in the terminal plates 38 and 39 respectively. The thicknesses of the terminal plates 38 and 39 and spacer nuts iii and 2l! are approxiamtely equal to the thickness of the lower half 25 of the flame proof shell 2l.

Clamping nuts `lili and M lock the limiter and the terminal plates to the tie bar to form a unitary assembly.

The sides of the tie bar l@ may be recessed as at d2, see Fig. 3, to receive the spring head of the clip `i3 which supports the flame-proof shell 2l to the tie bar during the assembly. The two halves of the shell may be uncemented if the clip 43 is used.

The tie bar and assembly may be mounted on the mounting plate lili by first interposing an insulating sheet i5 therebetween, perforated to receive the two flat head mounting screws 46 and Lil, inserted into the apertured recesses 48 and l of the upper surface of the tie bar. The mounting screws extend through apertured nut plate 5i), and the special vibration-proof lock nuts El and 52 are formed thereon.

It will be evident by the described construction that the limiter and flameproof shell may be attached to and removed from the supporting tie block as a single unit.

The construction illustrated accomplishes the further objects of my invention. The device is adaptable to mass production methods and is simple to install. The particular link illustrated is not affected by large variations in ambient temperatures and the electric circuit can be quickly cleared without arcing or sputtering. Further, the link is designed to carry heavy currents for predetermined periods of time, without fusing.

I have thus described my invention, but I desire it understood that it is not conned to the particular forms or uses shown and described, the same being merely illustrative, and that the invention may be carried out in other ways Without departing from the spirit of my invention, and, therefore, I claim broadly the right to employ all equivalent instrumentalities coming within the scope of the appended claims, and by means of which, objects of my invention are attained, and new results accomplished, as it is obvious that the particular embodiments herein shown and described are only some of the many that can be employed to attain these objects and accomplish these results.

What I claim and desire to secure by Letters Patent, is as follows:

1. A current limiter for detachably securing a pair of conductors thereto, said current limiter comprising a metallic fuse link having two exposed ends provided with detachable engaging means, and an intermediate fusible element made of the same piece of metal as the two ends; a

flame-proof enclosure secured to the fuse link, permitting the two exposed ends of the fuse link to extend therefrom; an insulating supporting means positioned adjacent the fuse link, having a securing means positioned at each end of the insulated supporting means for simultaneously and detachably securing a conducto-r and an end of the fuse link to each other and both the conductor and the fuse link to the insulating supporting means by said securing means.

2. The current limiter of claim l wherein the flame-proof enclosure is permanently secured to the fuse-link with exposed ends, by non-metallic means.

JULIAN ROGOFF.

REFERENCES CITED The following references are of record in the file oi this patent:

UNITED STATES PATENTS OTHER REFERENCES Page 1195, Electrical Engineering, Sept. 1937, published by the American Institute of Electrical Engineers, New York, N. Y. 

